A rapid thin-layer chromatographic method has been developed for comparing the different ethoxylation products during the manufacture of non-ionic surfactants. The ethoxylation products are separated on silica gel layers with ethyl acetate-acetone-water (12:5:0.5) as mobile phase. The chromatograms were visualized by exposure to iodine vapor for 3 min; densitometric scanning was then performed at 460 nm in reflectance mode and plates were evaluated by use of RF values and peak-area data. The separation conditions were investigated and optimized. The average numbers of the oxyethyl groups in the molecules of the adducts, and their distribution curves, were determined and used as criteria for monitoring the extent of ethoxylation of the intermediates and the final products. The method is recommended for the purpose because of the advantageous features of TLC.